I had a good time reading everyone's thoughts on the Mac Mini Pro and how to handle external storage. I toss in my thoughts here too if I may -
Some of us fall into the camp of not being a major fan of Drobo. I'll just say that I'd rather have this item instead or similar - Areca Arc 8050. Barefeats has a nice review here -
http://barefeats.com/hard167.html
DAS and NAS - I have both and they are purposed very differently. If one is going to throw a couple of coins out for the Mac Mini Pro, they should put careful consideration on what they are doing and how to avoid bottlenecks and at the same time hopefully be able to exploit any drives (internal and external) that they have already or be ready to populate with new drives (electro-mechanical or SSD).
Staying a bit green on DAS. This is a tough one. You buy a largish item like the Drobo or Areca and all drives are ready to go along with some power consumption. People who have USB 3 external drives might fair well for non speed intensive work. - Again, there are considerations for utility and how much electricity you are ready to pay for to get the Mac Mini Pro where you want it for whatever you use it for.
As far as TB1 vs TB2, if one goes with some DAS RAID set up with 3 or more drives, TB2 might be a better fit if you hang other devices on the TB line. TB1 is great for single drives, SSD singles, monitors and the like. This is just an opinion based on reading various discussions on the value of TB in general.
In a kinder world, someone would make a hybrid enclosure that was both NAS and DAS. Ethernet NAS with direct TB connection. This would solve a lot of issues. Then again, long long long ago on a couple of NAS forums, I had a wish for iSCSI and 2 years later, its become a regular item though not very well implemented.
Items I might add to a Mac Mini Pro set up -
The fore-mentioned Areca for RAID type business.
Firmtek's USB3 2.5 inch enclosure with SSD (fastest enclosure in its class)
NAS (QNAP, Synology, Thecus, etc..take your pick)
SSD - Samsung Evo and Pro lines
Electro-mechanical drives - again take your pick based on how it will be used but for NAS I might venture to remain with either enterprise level or the prosumer WD Reds and "VN" Seagates.
To be candid, I am not sure the Mac Mini Pro is for me for two reasons beyond cost - the graphics dual set up at present has little value to most, the way Apple populates RAM is just plain wrong and as a "pro" machine why does the base start with 256 SSD which is today, rather pathetic. Since I have voiced this negative my hope would have been for single GPU, base RAM 2x8 = 16 populated, 500 gig SSD and all for the same price as what they are offering now for the base model. This would be more in line for pro work.
For now, I'll wait for the new Mac Mini and see what it has to offer. The Mac Mini Pro for many will be a great machine but have facets that wont truly be exploited (dual gpu comes to mind) unless Apple's OSX has some trick up it's sleeve to further exploit the chips of the GPU and re-purpose them when not doing "dual" work.
Just more peanuts from the gallery.
At any rate, the reason you're a fan of parity RAID is for the right reasons... business continuity. But I'm honestly surprised you haven't been burned with rebuilding large multi-TB arrays. There's certainly a lot of discussion out there these days about the merits of large disk parity RAID setups. At least if you're going to setup a parity RAID array... go RAID6 like you did. RAID5 is asking for trouble. But for normal folk JBOD is much more practical and makes a lot more sense.
